Degradation Of Oxytetracycline Hydrochloride Research Articles

Synergistic degradation of oxytetracycline hydrochloride by persulfate activated by Ni-doped MIL-88A three-dimensional catalyst: Free radical and non-free radical pathways

The advanced oxidation technology of persulfate has great potential in removing pollutants. Appropriate bimetallic activation method has obvious synergistic effect on the formation of free radicals and non-free radicals, and can also promote the electron transfer process. Therefore, in this paper, Ni was doped on the iron-based metal organic framework (MIL-88A) to form bimetallic catalyst and used as persulfate activator for oxytetracycline (OTC) degradation. The introduction of Ni increased the specific surface area of the catalyst and significantly improved its catalytic performance. Within 30 min, the degradation efficiency of 5 mg/L OTC reached 81.30%. The used catalyst can be simply recovered by standing, and the catalytic stability is high. The composition of main reactive oxygen species (ROS) in pollutant decomposition was clarified through the analysis of degradation mechanism. In addition to typical •OH、SO4•− and O2•−, non-free radical 1O2 was also generated. Based on LC-MS detection and toxicological experiments, the possible degradation pathways were proposed and the toxicity was analyzed. This material provides a new insight for activating PS to remove refractory organic compounds, and promotes the application of Fe-MOF materials in environmental pollution remediation.

Microwave assisted biomass derived carbon aerogel for highly efficient oxytetracycline hydrochloride degradation: Singlet oxygen mechanism and C vacancies accelerated electron transfer

With plant biomass α-cellulose and sodium lignosulfonate as starting materials, biochar aerogel catalysts were prepared with facile microwave assisted pyrolysis in 5 min; and the as-prepared biochars were utilized for efficient peroxymonosulfate (PMS) activation and oxytetracycline hydrochloride (OTC) degradation under transition metal free conditions. It was found that microwave treatment and sodium lignosulfonate were beneficial for thiophene S introduction, C = O groups and C vacancies enrichment, as well as specific surface area increase. The optimal α-cellulose and sodium lignosulfonate derived metal free biochar aerogel catalyst C3S2 displayed excellent ability to promote PMS activation for 99.9 % OTC degradation during 15 min with rate constant up to 0.818 min−1. Through correlation analysis, quenching tests as well as EPR characterization, C = O groups and thiophene S were considered as main sites for PMS activation to produce nonradicals singlet oxygen (1O2) in OTC degradation. Meanwhile, C vacancies enrichment further improved the pollutants degradation by means of electron transfer acceleration. This research demonstrated new insight in metal-free biochar catalyst design for highly efficient contaminants degradation with 1O2 pathway.

Photodegradation of oxytetracycline hydrochloride by Z-scheme g-C3N4 @MIL-101(Fe) heterojunction: Experimental optimization, mechanism evaluation and practical application

The residues of oxytetracycline hydrochloride (OTC) in water have potential adverse effects on human health and ecological environment. Photocatalytic degradation has been widely studied in the treatment of antibiotic pollution due to its environmentally friendly and efficient characteristics. However, the band gap of traditional photocatalysts is too wide, and the recombination of photogenerated electrons and holes is serious, which has negative effects on photocatalysis. Therefore, the Z-scheme heterojunction g-C3N4@MIL-101(Fe) composite photocatalyst was synthesized by high temperature calcination combined with solvothermal method. g-C3N4@MIL-101(Fe) was characterized by XRD, FTIR, SEM, TEM and other tests. All the results showed that the compound was successful A series of photoelectric tests showed that g-C3N4@MIL-101(Fe) has a narrower band gap, stronger light absorption ability, and improved the separation rate of photogenerated electrons and holes. Under visible light irradiation, g-C3N4@MIL-101(Fe) could remove 87.68% of OTC in 300 min. g-C3N4 @MIL-101(Fe) showed good potential for practical application in five real water samples and stability after six cycles. Finally, superoxide radicals and hole radicals were identified as the main reactive species in the photodegradation process. The mechanism and pathway of the photocatalytic degradation of OTC by g-C3N4@MIL-101(Fe) are proposed. This work expands the construction and application of Fe-MOF based Z-scheme heterostructure and provides a new idea for water pollution remediation.

Preparation of Fe3O4@GO@MIL-101 nanocomposites and efficient degradation of oxytetracycline hydrochloride by promoting charge separation during the photo-Fenton process

The combination of photocatalysis and Fenton oxidation technology is an efficient strategy to improve the efficiency of oxytetracycline hydrochloride (OTC-HCl) degradation. Herein, a Fe3O4@GO@MIL-101 composite catalyst bridged with graphene oxide (GO) was obtained by a two-stage hydrothermal method. The introduced graphene oxide layer could inhibit the recombination of electron hole (e−- h+) pairs by attracting photo-generated electrons from MIL-101 and transferring them to Fe3O4, observably enhancing the photocatalytic performance of the composite Fe3O4/MOFs. Under the optimal conditions (initial pH, 10 mmol H2O2, 0.01 g/L catalyst), the Fe3O4@GO@MIL-101 + H2O2+Vis system could achieve a degradation effect of 97.26 % on 70 mg/L OTC-HCl within 50 min Fe3O4@GO@MIL-101 nanocomposites exhibited good recyclability, were easy to recover after multiple uses, and maintained excellent removal efficiency for pollutants. A series of data demonstrated that in Fe3O4@GO@MIL-101 + H2O2+Vis system, the primary active substances involved in OTC-HCl degradation were holes and superoxide radicals, while the contributions of hydroxyl radicals and photo generated electrons were relatively weak. Finally, based on various characterization results and catalyst activity performance, a feasible mechanism for the removal of OTC-HCl by Fenton-like system was proposed.

Boron-doped biochar-nano loaded zero-valent iron to activate persulfate for the degradation of oxytetracycline

Oxytetracycline has posed a serious environmental nuisance, and seeking environmental decontamination materials is the priority task to deal with antibiotic water contamination. Herein, boron-doped biochar loaded nano zero-valent iron composites (nZVI/BBC) were fabricated as activators of PDS for oxidative degradation of oxytetracycline hydrochloride (OTC), and the main removal mechanism was explored in detail. The results showed that Boron-doped biochar with borate ester structure (BC2O) and degree of defects are the main active sites for improving PDS activation properties. BBC could effectively prevent nZVI agglomeration and reduce nZVI passivation. The effects of calcination temperature of BBC, loading ratio and dosage of nZVI/BBC, PDS concentration, initial solution pH, pollutant concentration, and interfering ions on OTC removal by nZVI/BBC were also systematically investigated, and the optimal reaction conditions were screened: 10 wt% loading of nZVI in the composite, 1 g/L dosage of nZVI/BBC, 1 mM dosage of PDS and solution pH= 5. The cycling test showed that the removal rate of OTC by nZVI/BBC decreased from 95.3% to 70.2% after five cycles, indicating that there is excellent stability of this material. Among them, the catalyst of 10%nZVI/BBC displayed the optimal PDS activation performance, owing to the synergistic adsorption-double oxidation system, BBC as well as nZVI. The free radical quenching experiment and free radical trapping experiment proved that the degradation of OTC mainly followed the free radical pathway and SO4•− and •OH were the primary active species in the catalytic system. This study provides a practical reference for the treatment of actual antibiotic wastewater.

Zero-dimensional N-doped carbon quantum dots and palladium co-modified titanium electrodes enhance the electrocatalytic degradation of oxytetracycline hydrochloride

Reducing the amount of precious metals and improving their catalytic activities are difficult problems in the field of electrocatalysis. In this study, Pd/N-CQDs/Ti electrodes were prepared by introducing the N element into zero-dimensional carbon quantum dots and then compounded with Pd metal, and the electron transfer mechanism was explored. The results showed that the composite electrode degraded OTC up to 90.41% (60 min) at natural pH with an energy consumption of only 0.288 kWh/m3. The Pd/N-CQDs/Ti electrode formed a Pd-N-CQDs interface due to the electronic metal-carbon interaction (EMCI). In this, electrons are transferred from Pd to N, and the Pd-N interface plays a major role in hydrogen precipitation and the generation of atomic hydrogen. The generated H* ,·OH, and HClO all contribute to the degradation of OTC. According to the cycling experiments, the Pd/N-CQDs/Ti electrode showed good stability. When applied to OTC degradation in real water bodies, good reactivity was still maintained. Toxicity assessment of the degradation intermediates by ECOSAR and TEST showed that the electrode could effectively reduce the biotoxicity of OTC. In this study, the interface of the catalytic electrode was tuned to enhance its intrinsic activity, which provides an efficient strategy for electrocatalytic remediation of antibiotic contamination.

Enhanced visible light induced photocatalytic degradation of oxytetracycline hydrochloride by n-ZnO/p-NiO composite

A series of porous n-ZnO/p-NiO with different Ni/Zn mass ratios photocatalysts were synthesized by a facile hydrothermal and calcination method. XRD, SEM, TEM, BET, XPS, FTIR, UV–vis analytical methods were used to characterize the composites. The results showed that, the composite material with a Ni/Zn mass ratio of 0.3 had a better photocatalytic effect, decomposing 79% of OTC-HCl in only 2 h. The increased photocatalytic activity might be attributed to the heterojunctions between n-ZnO and p-NiO. Notably, the photocatalysts had excellent stability. The scavenging experiments showed that O2− was the main active species in the photocatalytic degradation process.

BaTiO3/CeO2 heterojunction photocatalysts: design, construction and a novel application for the photocatalytic degradation of oxytetracycline hydrochloride

Abstract A polyacrylamide gel method combined with low temperature calcination technology has been developed to synthesize the BaTiO3/CeO2 heterojunction photocatalysts, which were formed by hybriding the large BaTiO3 particles and fine CeO2 nanoparticles with varied mass percent of CeO2. Various characterization methods have been used to determine the phase structure, functional group information, elemental composition, microstructure, optical and photocatalytic activity of BaTiO3/CeO2 heterojunction photocatalysts. The introduction of CeO2 into the host lattice of BaTiO3 does not change the optical band gap value (Eg = 3.20 eV) of the host lattice. As expected, the BaTiO3/CeO2 heterojunction photocatalysts exhibit highly enhanced and CeO2 composition-dependent photocatalytic activity for the degradation of oxytetracycline hydrochloride under simulated sunlight irradiation. The BaTiO3/5 wt% CeO2, BaTiO3/10 wt% CeO2, and BaTiO3/15 wt% CeO2 showed lower photocatalytic activity, while BaTiO3/20 wt% CeO2 showed highest photocatalytic activity (96.89 %) over the single component BaTiO3 and CeO2 photocatalysts with the initial oxytetracycline hydrochloride concentration, photocatalyst content and irradiation time were 100 mg/L, 1.5 g/L and 120 min, respectively. The enhanced photocatalytic activity of BaTiO3/20 wt% CeO2 heterojunction photocatalysts is ascribed to the cooperation between Ce3+ and Ce4+, improved charge transfer and separation of electron-hole pairs generated on irradiation with simulated sunlight and proper amount of surface defects or oxygen vacancies on the BaTiO3/CeO2 heterojunction photocatalysts.

Graphitic carbon nitride photocatalyst for the degradation of oxytetracycline hydrochloride in water

A common antibiotic, oxytetracycline hydrochloride (OTC) is hardly biodegradable due to its complex structure, hence is harmful to the environment. Photocatalysis is often performed using metallic photocatalysts and causes secondary pollution. The novelty of this study is that in this paper, graphitic carbon nitride (GCN), a metal-free photocatalyst was employed to degrade OTC via photocatalysis. Three low-cost carbon and nitrogen-rich precursors namely urea, thiourea and melamine were employed to synthesize the GCN (GCN-Urea, GCN-Thiourea, GCN-Melamine) and their abilities to degrade OTC were investigated. This is a prior study in investigating the effect of GCN synthesizing using precursors in degrading antibiotics OTC. FTIR and XRD analysis depicted that GCN photocatalysts were successfully synthesized using the three different precursors. SEM micrographs showed that GCN-Urea particles are ultrathin while GCN-Thiourea and GCN-Melamine are bulky, contributing to high surface area of GCN-Urea at 73.62 m2/g, while GCN-Thiourea and GCN-Melamine have surface area merely at 5.82 and 3.99 m2/g. Meanwhile, GCN-Urea has the highest band gap at 2.7 eV, followed by GCN-Melamine and GCN-Thiourea and are 2.3 and 2.2 eV respectively. GCN-Urea demonstrated the highest capability to absorb light and to induce effective transmission of photoinduced electron-hole, proven by UV–Vis spectra, EIS, Cyclic voltammetry and photocurrent analysis. The best OTC degradation performance was achieved by GCN-Urea at ∼60%, which was 2.5 times higher than GCN-Thiourea and GCN-Melamine. e− and ⸳OH are the main photocatalytic radical species, and GCN-Urea exhibited good stability after being recycled in four cycles.

Carbon nanotube-loaded copper-nickel ferrite activated persulfate system for adsorption and degradation of oxytetracycline hydrochloride

In this study, a new composite (MWCNTs-CuNiFe2O4) prepared by loading magnetic CuNiFe2O4 particles onto carboxylated carbon nanotubes (MWCNTs) through co-precipitation was applied to remove oxytetracycline hydrochloride (OTC-HCl) in solution. The magnetic properties of this composite could address of the issue of difficulty associated with the separation of MWCNTs from mixtures when applied as an adsorbent. In addition to the good adsorption properties recorded for MWCNTs-CuNiFe2O4 towards OTC-HCl, this developed composite could be used to activate potassium persulfate (KPS) for an efficient degradation of OTC-HCl. The MWCNTs-CuNiFe2O4 was systematically characterized using Vibrating Sample Magnetometer (VSM), Electron Paramagnetic Resonance (EPR) and X-ray Photoelectron Spectroscopy (XPS). The influence of dose of MWCNTs-CuNiFe2O4, the initial pH, the amount of KPS and the reaction temperature on the adsorption and degradation of OTC-HCl by MWCNTs-CuNiFe2O4 were discussed. The adsorption and degradation experiments showed that MWCNTs-CuNiFe2O4 exhibited an adsorption capacity of 270 mg·g−1 for OTC-HCl with the removal efficiency 88.6% at 303 K (at an initial pH 3.52, 5 mg KPS, 10 mg composite, 10 mL reaction concentration 300 mg·L−1 of OTC-HCl). The Langmuir and Koble-Corrigan models were used to describe the equilibrium process while the Elovich equation and Double constant model were suitable to describe the kinetic process. The adsorption process was based on single-molecule layer reaction and non-homogeneous diffusion process. The mechanisms of adsorption were complexation and hydrogen bond whereas active species such as SO4‧-, ‧OH and 1O2 were confirmed to have played a major role in the degradation of OTC-HCl. The composite was also found to be very stable with good reusability property. These results confirm the good potential associated with the use of MWCNTs-CuNiFe2O4/KPS system for the removal of some typical pollutants from wastewater.

Degradation of oxytetracycline hydrochloride using photocatalysis in the presence of Fe3O4/rGO/Co-doped ZnO/g-C3N4 nanocomposite particles: Experiment, modeling, optimization and mechanistic evaluation

In recent years, semiconductor materials have shown excellent potential in the field of photocatalytic degradation of antibiotics. To prepare a photocatalyst with excellent performance, an Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 tetrameric hybrid photocatalyst was successfully prepared for the first time by means of chemical precipitation using graphene oxide as the precursor. The developed quaternary photocatalyst was used for the degradation of oxytetracycline hydrochloride (OTC), and its photocatalytic activity was investigated. The structure and morphology of the composites were characterized by XRD, SEM, HR-TEM, ESR, N 2 adsorption, PL spectroscopy and UV-Vis DRS. The effects of different parameters on the degradation process were studied by the response surface method and artificial intelligence. The results showed that Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 was successfully synthesized. Under optimal conditions, the degradation rate of OTC was approximately 82% (the Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 dose was 0.16 g, the pH was 7.0, the initial concentration of OTC was 30 mg/L, and the visible light irradiation time was 70 min). pH is the most influential variable for OTC removal. At the same time, the degradation rate of OTC remained above 50% after 5 times of recycling, indicating that Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 photocatalyst had good stability and recoverability. In addition, the results of ESR and radical trapping experiments showed that ·O 2 - and ·OH were the main active species in the OTC removal process. • The prepared tetrameric hybrid photocatalyst effectively degrades oxytetracycline hydrochloride. • Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 nanomaterials are rapidly separated after the degradation process. • Artificial intelligence is used to model and optimize the degradation process. • ∙OH and ∙O 2 - are the main oxidizing species.

Fabrication of a Plasmonic Heterojunction for Degradation of Oxytetracycline Hydrochloride and Removal of Cr(VI) from Water

A novel Ag/Ag2CO3/BiVO4 plasmonic photocatalyst was successfully prepared by depositing Ag nanoparticles on the surface of Ag2CO3/BiVO4 through the photoreduction reaction. Due to the existence of this novel heterojunction photocatalyst structure, not only can it prevent the photogenerated charge recombination, but the unique properties of Ag also have a great advantage in the absorption of light. The Ag/Ag2CO3/BiVO4 photocatalyst showed good catalytic performance in the degradation of oxytetracycline hydrochloride (OTH) and removal of Cr6+, and the degradation rate of OTH reached 98.0% after 150 min of illumination. The successful preparation of Ag/Ag2CO3/BiVO4 was confirmed by a series of characterization methods, and the importance of •OH and h+ radicals in the degradation of OTH was demonstrated. In addition, the photocatalytic mechanism of Ag/Ag2CO3/BiVO4 photocatalyst was systematically studied in terms of degradation of OTH and reduction of Cr6+. This study is of great importance for the development of novel plasmonic heterojunction photocatalysts and to meet future environmental requirements.

Strongly coupled FeOOH nanoparticles/O doped g-C3N4 nanosheets for visible-light-driven effective treatment of oxytetracycline hydrochlorides

This study rationally designed a novel heterogeneous photocatalyst through in situ precipitation of amorphous FeOOH nanoparticles on the porous oxygen doped g-C3N4 nanosheets (FeOOH NPs/O-CNNS). The synergistic effect of FeOOH coupling and O doping promoted the photocatalysis degradation for the oxytetracycline hydrochloride (OTC) from 55.47% to 78.95% in 90 min, with TOC mineralization efficiency of 45%. Meanwhile, the optimal conditions in FeOOH NPs/O-CNNS/vis system predicted by the response surface method (RSM) were provided below: the catalyst dosage is 0.594 g/L, the electricity is 17.665 A, the initial pH is 5.82, and OTC degradation can reach 81.337%. FeOOH coupling could greatly reduce carriers’ recombination and broaden visible light absorption range, and O doping could form Fe-O bond for the strongly coupled interface and also optimize electronic structure to promote the dissociation of excitons. FeOOH NPs/O-CNNS catalyst had potentially practical application for high (10 mg/L) and low (1 μM) OTC pollution under natural light irradiation. Based on the liquid chromatograph mass spectrometer analysis (LC-MS), the possible degradation pathway of OTC was proposed, and meanwhile combined with quantitative structure activity relationship (QSAR) prediction, the harmless treatment of OTC pollution by FeOOH NPs/O-CNNS photocatalysis could be achieved.

Integration of plasmonic effect and S-scheme heterojunction into gold decorated carbon nitride/cuprous oxide catalyst for photocatalysis

A plasmonic Step-scheme heterojunction Au/g-C 3 N 4 /Cu 2 O photocatalyst was fabricated for the degradation of pollutants and energy generation . The removal of pollutants (oxytetracycline hydrochloride , OTH) and hydrogen evolution experiments showed that the catalyst had satisfactory stability and perfect photocatalytic performance. Among these catalysts, the 4-Au/g-C 3 N 4 /Cu 2 O displays the highest catalytic performance with the OTH removal efficiency as high as 94.8%. For the catalytic H 2 evolution, the 4-Au/g-C 3 N 4 /Cu 2 O reveals the optimal H 2 generation rate (552.6 μmol g −1 . h −1 ), which is about 13.4 times higher than that of the bare Cu 2 O sample. The satisfactory photocatalytic performance can be attributed to the efficient interfacial charge separation, the high light absorption capacity induced by localized surface plasmon resonance (LSPR) of Au nanoparticles , and the formation of Step-scheme heterojunction retaining strong photocatalytic oxidation and reduction capability. The charge density difference was also calculated to verify the existence of the built-in electric field, which was the driving force for the formation of Step-scheme heterojunction structure. • Step-scheme Au/g-C 3 N 4 /Cu 2 O was synthesized for oxytetracycline hydrochloride degradation and hydrogen generation. • Internal electric field will assist charge transfer. • The charge density difference between g-C 3 N 4 and Cu 2 O was calculated. • A plasmonic Step-scheme photocatalytic mechanism was proposed based on the experiments and simulations.

Photocatalytic oxidation of oxytetracycline hydrochloride by using natural marine material supported perovskite composites

The photocatalytic performance of LaCuO3/CFB (CFB: Cuttlefish bone) composite catalyst was investigated for the degradation of the veterinary antibiotic oxytetracycline hydrochloride. The composite catalyst was characterized by SEM, XRD, XPS, BET, and FT-IR analyzes. The interactive influences of catalyst loading, pH and oxidant dosage on oxytetracycline hydrochloride degradation was investigated by using Box-Behnken Design. Reaction conditions were optimized at 0.77 g/L of catalyst loading, pH 4 and 3.46 mM of H2O2 dosage, and the antibiotic removal efficiency reached to 83% at these conditions. According to the kinetic study, the oxytetracycline hydrochloride oxidation followed second order reaction kinetics.

Preparation and characterization of ternary composite photocatalyst for degradation of oxytetracycline hydrochloride in seawater under visible light

Oxytetracycline hydrochloride is the most widely used veterinary antibiotic in aquaculture. The presence of large amounts of residual antibiotics in aquaculture wastewater harms the ecological environment. In this study, the ternary composite of Zn0.75Mn0.75Fe1.5O4/ZnFe2O4/ZnO (ZMF-ZF-Z) photocatalyst was prepared by the coprecipitation method for degradation of oxytetracycline hydrochloride in marine aquaculture wastewater. The crystal phase, structure, morphology, elemental composition, element content, and optical properties of photogenerated electron-hole pairs of catalyst were characterized by XRD, SEM, EDS, UV-VIS (DRS), PL spectroscopy, and other test methods. The results showed that ZMF-ZF-Z photocatalyst had a larger response range of visible light than pure ZnO, which can absorb more natural light. During the process of the experiment, the photocatalytic effect of Z ZMF-ZF-Z photocatalyst was almost no weakening after 5 times reuse, which means quite good stability of the photocatalyst. Under the visible light irradiation, the degradation rate of oxytetracycline hydrochloride in seawater was 77.11% with ZMF-ZF-Z photocatalyst, which was about 3 times higher than that of pure ZnO, and the photocatalytic activity was significantly improved. This research provides a scientific and effective method for degrading antibiotics in seawater in actual production and life.

FeOOH coupling and nitrogen vacancies functionalized g-C3N4 heterojunction for efficient degradation of antibiotics: Performance evaluation, active species evolution and mechanism insight

In this study, the highly active g-C3N4-based photocatalysts were first constructed by assembling amorphous FeOOH nanoparticles on g-C3N4 nanosheets with nitrogen defects (FeOOH NPs/Nvac-CNNS). Such photocatalysts showed 92.83% and 73.86% degradation and mineralization efficiency of the oxytetracycline hydrochloride (OTC) within 90 min, respectively. Meanwhile, Response Surface Method (RSM) predicted that under optimal conditions (electricity 18.586 A, initial pH 6.371 and dosage 0.6 g/L), OTC degradation efficiency of 94.331% can be achieved. FeOOH NPs/Nvac-CNNS exhibited the excellent reutilization and practical application potential in OTC pollution purification of high and low concentration. The synergistic effect of N vacancies and FeOOH coupling endowed CNNS with advantages, such as the carrier’s fast separation, good visible-light adsorption, H2O2 fast decomposition and excellent molecular oxygen activation. Such advantages greatly contribute to OTC efficient removal in water. Based on the liquid chromatograph-mass spectrometer (LC-MS) analysis, the five possible degradation pathways of OTC were provided. Furthermore, through the quantitative structure-activity relationship (QSAR) analysis, biological toxicity prediction results of OTC and its intermediates indicated that the FeOOH NPs/Nvac-CNNS/vis system had great potential to achieve green and harmless treatment of OTC pollution.

Synthesis of a novel Z-scheme Ag/WO3/g-C3N4 nanophotocatalyst for degradation of oxytetracycline hydrochloride under visible light

In this work, Ag/WO3/g-C3N4 (AWC) nanocomposites were successfully prepared via a hydrothermal method. Oxytetracycline hydrochloride (OTC) was used to evaluate the photocatalytic activity of the photocatalysts under visible light. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra (Raman), scanning electron microscope (SEM), Ultraviolet–visible spectroscopy (UV–vis DRS), photocurrent density (I-t) and electrochemical impedance spectra (EIS). The results showed that WO3 and Ag nanoparticles were coupled with g-C3N4 successfully. Comparing with pure WO3 or g-C3N4, the visible light absorption region of AWC composites was effectively broadened. The photocatalytic performance experiment illustrated that AWC-2 composite had the highest photocatalytic activity, and 97.74% of OTC (10 mg/L) was degraded in 60 min with 0.4 g/L of AWC-2. The radical scavenging experiments indicated that the superoxide radical (•O2−) and hydroxyl radical (•OH) were the most important active species for OTC oxidation. The five cycle photocatalysis experiment further proved that AWC is a stable photocatalyst for degradation of OTC. Finally, the possible degradation mechanism of Z-scheme heterostructure photocatalysis was proposed according to the experimental results.

Synthesis of novel ternary Ag/BiVO4/GO photocatalyst for degradation of oxytetracycline hydrochloride under visible light

A ternary visible light responsive photocatalyst, Ag/BiVO 4 /graphene oxide (GO) composite was synthesized successfully using hydrothermal method. The prepared photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis absorption spectroscopy, Raman spectra, photocurrent density and EIS analysis. The photocatalytic activity of Ag/BiVO 4 /GO (ABG) nanoparticles was tested on the removal efficiency of oxytetracycline hydrochloride (OTC) in aqueous phase. Compared with pure BiVO 4 and binary composites BiVO 4 /GO (BG), the fabricated ternary composite ABG exhibited the enhanced photocatalytic activity to degrade refractory organic pollutant. 90.43% OTC was removed with 0.4 g/L ABG composite after 70 min visible light irradiation. The enhanced photocatalytic ability was due to the addition of Ag and GO, which promoted the charge separation. The reusable performance for the degradation of OTC showed that 86.74% removal efficiency was maintained even after five recycles. Active species trapping experiments demonstrated that the photo-produced holes (h + ) and O 2 - played a crucial role in photocatalytic degradation of OTC. Finally, the photocatalytic mechanism was proposed. This work provided a simple preparation method for a ternary photocatalyst with greatly enhanced photocatalytic ability.

Study on removal of oxytetracycline hydrochloride in marine aquaculture wastewater by Zn0.75Mn0.75Fe1.5O4/ZnFe2O4/ZnO photocatalyst

AbstractPhotocatalytic degradation of oxytetracycline hydrochloride (OTC‐HCl) in marine aquaculture wastewater and therefore the effects of factors on the effectiveness of photocatalysts are studied in this paper using Zn0.75Mn0.75Fe1.5O4/ZnFe2O4/ZnO under visible light and changing the molar ratio of Zn2+:Fe3+:Mn2+, calcination temperature of catalysts, hydrogen peroxide concentration, dose of catalysts, illumination time of photocatalytic and initial concentration of OTC‐HCl. The degradation of OTC‐HCl in marine aquaculture wastewater was optimized by orthogonal experiment. The best effect exists when the molar ratio of Zn2+:Fe3+:Mn2+ was 10:1:3, the calcination temperature of photocatalyst was 400°C, the concentration of hydrogen peroxide was 0.5 g/L, the dose of catalysts was 0.6 g/L, the illumination time was 2.5 h and the initial concentration of OTC‐HCl was 0.010 g/L. The degradation rate of OTC‐HCl can reach 80.18%. Zn0.75Mn0.75Fe1.5O4/ZnFe2O4/ZnO can effectively degrade the OTC‐HCl in marine aquaculture wastewater under visible light.